1. Field of the Invention
The present invention relates to an article transfer apparatus and, more particularly, to an article transfer apparatus suitable to vertically move an article such as wafer, panel or computer hard disc to a desired position.
2. Description of the Related Art
Generally, in the manufacturing process of a semiconductor device or electronic appliance, there is a need of an apparatus equipped with an arm that is designed to make a horizontal or vertical motion in order to move a wafer or hard disc to a desired position. FIG. 1 illustrates an example of the conventional apparatus for moving an article in the vertical direction, which is disclosed in U.S. Pat. No. 5,993,142.
Referring to FIG. 1, the apparatus comprises: a plurality of lead screws 2 and a driving motor (not shown) mounted on a base 1; a plurality of vertical structures 3 each having a hollow to receive the individual lead screws 2; an elevator 4 provided at the bottom end of the individual vertical structures 3 and engaged with the lead screws 2; a flange 5 provided at the top end of the individual vertical structures 3; a link L1 disposed between the vertical structures 3 and provided on the top of the flange 5; links L2 and L3 connected in series to the one end of the link L1; and a motor 6 and an end effector 7 connected to the end of the link L3.
Once the driving motor (not shown) mounted on the base 1 operates, the lead screws 2 associated with the motor via a belt is turned so that the elevators 4 engaged with the lead screws 2 are moved up or down depending on the direction of rotation of the motor. The vertical structures 3 correspondingly make an up-and-down motion in a telescopic manner, thereby moving an article placed on the end effector 7 to a desired position.
Such a conventional apparatus as constructed above, however, has the individual vertical structures vertically climbing in a telescopic manner along the lead screws and thus occupies a vertical space as high as the height of the lead screws even in the off state. It is thus disadvantageous in that the apparatus has a non-conveyable region as large as the height of the lead screws in the off state.
Furthermore, the conventional apparatus requires excessively many parts substantially necessary to the structure and consists of complex connections between the motor, the lead screws and the vertical structures, which leads to an increase in the production cost and the manufacturing period.
Accordingly, an object of the present invention to solve the problems is to provide an article transfer apparatus having a simple structure and operational mechanism, and requiring a short vertical working distance in a non-operated state.
To achieve the above object, there is provided an article transfer apparatus including: a base; a supporting shaft fixed on the base; a first link having one end pivotally coupled to the supporting shaft; a second link having one end pivotally coupled to the other end of the first link; a mounting member coupled to the second link and loadable with an article to be transferred; a driving motor for pivotally moving the first link with a swiveling force; a rotating shaft rotatably provided along the first link and rotated by the swiveling force of the first link; and a swiveling shaft having one end fixed on the one end of the second link, and the other end coupled to the rotating shaft of the first link, the swiveling shaft receiving the swiveling force of the rotating shaft and pivotally moving the second link.
A rotating bevel gear is provided on both ends of the rotating shaft, and a fixed bevel gear is provided on the one end of the supporting shaft and is engaged with the rotating bevel gear provided on the one end of the rotating shaft. And, a swiveling bevel gear is provided on the other end of the swiveling shaft and is engaged with the rotating bevel gear provided on the other end of the rotating shaft. Thus the pivotal motion of the first link causes the rotating shaft to be turned, and the swiveling force of the rotating shaft pivotally moves the swiveling shaft coupled to the second link, thereby pivotally moving the second link.
The rotating shaft includes: a first sub shaft having both ends each provided with a bevel gear, and the one end thereof engaged with the fixed bevel gear of the supporting shaft; a second sub shaft having both ends each provided with a bevel gear, and the one end thereof engaged with the swiveling bevel gear of the swiveling shaft; and a switching shaft rotatably mounted in the first link and having a rotating bevel gear concurrently engaged with both the bevel gears provided on the other ends of the first and second sub shafts.
Thus the pivotal upward or downward motion of the first link causes the second link to pivotally move in the same direction, i.e., upward or downward.
The rotating bevel gear of the switching shaft is engaged with the bevel gears of the first and second sub shafts at a gear ratio of 1:1, and the bevel gear of the second sub shaft is engaged with the bevel gear of the swiveling shaft at a gear ratio of 2:1. Accordingly, the swiveling angle of the second link is double the swiveling angle of the first link, so that both ends of the individual links are moved upward along the same axis.
The article transfer apparatus further includes: a second supporting shaft having one end fixed on the first link and the other end extending to the second link for pivotally supporting the second link and being coaxial with the swiveling shaft fixed on the second link; a second rotating shaft mounted along the second link to be rotated by the swiveling force of the second link; and a second swiveling shaft having one end fixed on the mounting member and the other end coupled to the second rotating shaft of the second link, the second swiveling shaft receiving the swiveling force of the second rotating shaft and pivotally moving the mounting member.
A rotating bevel gear is provided on both ends of the second rotating shaft, and a fixed bevel gear is provided on the other end of the second supporting shaft and engaged with the bevel gear fixed on the adjacent one end of the second rotating shaft. And, a swiveling bevel gear is provided on the other end of the second swiveling shaft and engaged with the bevel gear fixed on the adjacent other end of the second rotating shaft. Thus the pivotal motion of the second link causes the second rotating shaft to be turned, and the turning force of the second rotating shaft pivotally moves the second swiveling shaft together with the mounting member.
The bevel gear of the second rotating shaft provided on the second link is engaged with the bevel gear of the second supporting shaft fixed on the first link at a gear ratio of 1:1, and a bevel gear of the second rotating shaft is engaged with the bevel gear of the second swiveling shaft fixed on the mounting member at a gear ratio of 1:2. As a result, the swiveling angle of the mounting member is a half of the swiveling angle of the second link, so that the mounting member can be ascending while maintaining in parallel with the horizontal plane.
In another embodiment of the present invention, the second link includes a plurality of sub links serially coupled in the same manner as the engagement structure made between the first and second links, and the mounting member is provided on the final sub link. This elongates the vertical transfer distance of the mounting member.